A PRASEC-SCALE SUPERJET AND QUASI-PERIODIC STRUCTURE IN THE HH-34 OUTFLOW

We report the detection of a new Herbig-Haro (HH) object, HH 173, near the young stellar object HH 34* in the L1641 molecular cloud in Orion. The new object appears to be part of a remarkable bipolar chain that includes known HH objects in this region and extends symmetrically about HH 34* for 1.5 pc. The chain terminates in the north at the position of HH 33 and includes HH 40, HH 85, HH 126, and HH 34N. Toward the south, the chain ends at the position of HH 88 and includes HH 87, HH 86, HH 173, HH 34X, HH 34, and the HH 34 jet. All HH objects in the chain that have recognizable bow shock morphologies point to a driving source in the HH 34* cloud core. We propose that this chain delineates a 3 pc long bipolar outflow from HH 34* with blueshifted gas in the south and redshifted gas in the north. The quasi-periodic spacing of the HH objects may be a consequence of episodic mass-loss events from HH 34* occurring roughly every 900/V300 yr (for a flow velocity V300 measured in units of 300 km s-1). The dynamic age of the most distant HH object from HH 34* is approximately 5000 yr. The S-shaped symmetry of the HH objects about the central source may result from jet precession with a period of approximately 10(4) yr.